441. Arranging Coins

class Solution {

    /**
     * @param Integer $n
     * @return Integer
     */
    function arrangeCoins($n) {
        $layer = 0;
        while($n >= $layer) {
            $n -= $layer;
            if ($n >= ($layer + 1)) {
                $layer++;
            }
        }

        return $layer;
    }
}